Step 1

Preheat oven to 325 degrees F (165 degrees C).

Step 2

Bring water to a boil in a large pot. Cook sweet potatoes in boiling water until tender, about 7 minutes; drain. Transfer potatoes to a large mixing bowl; mash with a potato masher until smooth. Add 3/4 cup brown sugar, Tennessee whiskey, 1/4 cup softened butter, cinnamon, and nutmeg to the potatoes; stir to incorporate. Spread mixture into a 1-quart casserole dish.

Step 3

Melt 1/4 cup butter in a small skillet over low heat. Stir 3/4 cup brown sugar into the melted butter until incorporated. Add pecans to skillet; cook and stir until the pecans are completely coated in the butter mixture, 2 to 3 minutes. Top sweet potato mixture with the pecans.

Step 4

Bake in preheated oven until browned around the edges, about 25 minutes.